The wild sheep of North America are divided into two species, which are known as thinhorn sheep and bighorn sheep. Both species belong to the family Bovidae and genus Ovis. The thinhorn sheep of Alaska and Canada (Ovis dalli) are divided into two subspecies or races: Dall's sheep(Ovis dalli dalli) and Stone's

sheep (Ovis dalli stonei). Thinhorn sheep inhabit Alaska, British Columbia, the Northwest Territories, and the Yukon. Dall's sheep number approximately 100,000 and Stone's sheep number about 18,500.

 

As their name indicates, bighorn sheep have larger horns than thinhorn sheep. The taxonomy of bighorn sheep is being reanalyzed by several researchers; however, seven races of bighorn sheep (Ovis canadensis) have traditionally been recognized. A description of the distribution and abundance of each race is provided below.

 

​

Rocky Mountain bighorn (Ovis canadensis canadensis) are the most abundant and widespread bighorn race, numbering between 31,500 - 34,500. They are found in British Columbia, Alberta, Washington, Oregon, Idaho, Montana, Wyoming, South Dakota, Nebraska, Colorado, New Mexico, Utah, Nevada, and Arizona.

 

​

California bighorn (Ovis canadensis californiana) number approximately 10,500 rangewide and are found in British Columbia, Washington, Oregon, Idaho, California, Nevada, Utah, and North Dakota. The genetically distinct population of California bighorn inhabiting the Sierra Nevada of California was emergency listed as endangered by the U.S. Fish and Widlife Service in April 1999.

 

Nelson bighorn (Ovis canadensis nelsoni) are the most abunadant of the desert bighorn races and number approximately 13,000. These bighorn are found in California, Nevada, Utah, and Arizona.

 

Mexicana bighorn (Ovis canadensis mexicana) populations total roughly 6,000 bighorn, which are distributed across Arizona, New Mexico, Texas, Sonora, Chihuahua, and Coahuila. Mexicana bighorn sheep are listed as endangered by the state of New Mexico.

 

Peninsular bighorn (Ovis canadensis nelsoni) inhabit the Peninsular Ranges of Sourthern California and Baja California. Only approximately 950 remain within the U.S. and less than 2,500 are thought to remain in Baja California, Mexico. These bighorn have been listed as threatened by the state of California since 1971 and federally endangered within the United States by the U.S. Fish and Wildlife Service since March 1998.

 

Weems bighorn (Ovis canadensis weemsi) number less than 1,000 and are found only in Baja California Sur.

 

Audubon bighorn (Ovis canadensis auduboni) formerly inhabited parts of Montana, North Dakota, South Dakota, Nebraska, and Wyoming but were extinct throughout their range by 1925.

​

​